1. Field of the Invention
The present invention relates generally to the production of small transponder devices, and more particularly to a fully automatized method for manufacturing small passive transponder devices suitable for fitting into a small implantable capsule, including high speed automated core winding and fully automated wire-to-lead termination.
2. Brief Description of the Prior Art
Transponders have been used for identification purposes for many years, especially in the detection and identification of livestock. Passive transponders are usually self-contained implantable devices which are designed to have a longer useful lifetime than the life-span of the animal in which they are implanted.
A fundamental component of the transponder device is a semiconductor chip or die which contains the identification information. This chip is coupled to an induction coil which enables the transponder to receive and utilize incident electromagnetic wave energy for power and to retransmit electromagnetic response signals. Initially, an operator, using a hand-held or other type of transmitter/reader, directs a beam of energy toward the implanted transponder. This energy, usually in the form of an electromagnetic radio wave, induces a current in the induction coil which charges a minute capacitor or similar energy storage component. After being energized, the transponder device subsequently discharges the stored energy in the form of an electromagnetic wave which carries the identification information to an appropriate receiver, thus enabling identification of the transponder device carrier.
Because it is necessary for these devices to be implantable, there are inherent size restrictions that must be considered in their design and manufacture. For example, an element of most passive transponders is a ferrite core, around which a fine copper wire must be wound. This wire typically has a diameter of only a few microns, and is thus quite difficult to manipulate with precision and care, even manually. Consequently, prior art methods of manufacture require a relatively slow core winding speed, and manual bonding of the wire ends directly to the integrated circuit substrate. Thus, operator attention and interaction is continuously required to ensure the proper handling and connection of the delicate core wire. This is very costly, especially in terms of lost production time and the labor expense involved in constantly employing the highly trained technicians necessary for device assembly.
Another difficulty in the efficient production of these devices relates to the method used in encapsulating the semiconductor chip to which the fine core wire is attached. The usual method is to use a transfer molding process so that the delicate wires connecting the silicon die to the electrical connections on the leadframe are not disturbed or damaged. Transfer molding, however, involves a relatively lengthy cycle time, and thus an additional delay to the total production time necessary for the manufacture of the transponders is incurred.